Machine milking has been available for about a century. The basic construction of a milking device, which is still in use today is based on an invention patented by Gillies in 1902, and comprises a double chambered teat cup designed to operate with a pulsating vacuum. The teat cup comprises a flexible sleeve made of rubber, forming one flexible wall of a chamber, where the teat cup shell forms the other wall. In the space between the two walls a pulsating vacuum is applied whereby the sleeve will expand and contract, thereby causing a massaging action on a teat on which the teat cup has been applied.
The flexible sleeve is provided as a part of a so called teat cup liner (or inflation in U.S. English; in the present specification and claims the term “liner” will be used throughout).
A milking apparatus as a whole comprises a number of different components, many of which currently are made of different kinds of rubber, e.g. tubing, nozzles, liners etc.
As an example, a modern teat cup system is disclosed in U.S. Pat. No. 6,176,200 (Petterson). It comprises a tubular head portion capable of receiving a teat, and a shaft portion forming an inner wall of the pulsating vacuum chamber. The shaft portion is flexible and normally made of a rubber compound.
In order to be accepted by the market, devices forming the components of milking apparatus, such as teat cups and liners, must exhibit a number of properties. Examples that can be mentioned are the following:
Good milking performances, e.g., milk speed, milk yield, slip, strip yield
Good teat treatment
Long lifetime of the device and capability of functioning at the same high level of performance over the entire lifetime.
Uniform quality of the devices.
Chemical and physical endurance
Devices should be easy to clean
Devices should be easy to replace
Devices should be environmentally friendly, e.g., recycling of the material should be possible
The product must comply with regulations relating to material and to articles and products that are intended to come into contact with foodstuff.
Currently available components of milking apparatus, such as liners and tubing, are most often made of rubber materials, which do not meet the above requirements to a totally satisfactorily degree.